Coordinate measurement machines (CMM's) measure parts, typically during manufacture, by probing the part to be measured with a probe such as a probe tip either by physical contact of the probe tip to the part, or by non-contact means. Angular encoders or other means may be located in the joints of the CMM robotic arm segments which hold the probe tip, and thus the position of the probe tip may be measured in a convenient coordinate system of the user's choosing. The operations of the CMM can also be coordinated with a CAD system or software for example.
Different probes or end effectors are used for different applications. For example, some areas of an object to be measured are difficult to reach and thus require specifically sized or shaped probes to be used on the CMM. Therefore, probes are commonly interchanged depending upon the characteristics of the region to be measured.
However, calibration is often a time consuming issue when using CMM's, especially when differently sized probes are interchanged and recalibration is typically required. In an assembly line environment for example, taking a CMM off-line for twenty minutes so that it can be recalibrated when a probe tip is changed can cause problems. Thus, manufacturers endeavor to set up their CMM's so that interchangeability of probes may be accurately performed with a minimum of downtime due to recalibration. However, further innovations are necessary.
Applicants' company, FARO Technologies, Inc., has several patents related to CMM's or related areas, including: U.S. Pat. Nos. 5,611,147, 5,794,356, 6,612,044, 6,820,346, 6,796,048, 6,920,697, 6,965,843, the entire disclosures of which are hereby incorporated herein by reference.
An example of a current system in use is the Romer Simcor “Infinite” series that uses a specific pin system associated with each specific interchangeable probe. In this system, a set of specific probes can be interchanged and identified by the CMM using a physical and/or electrical pin orientation which is unique to each probe and which must be entered and stored into a memory located in the CMM for example for later recognition. Thus, the number of probes that are useable is limited by the possible pin orientations. Also, probes of the same size/type cannot be distinguished. Additionally, a manual initial set-up and entry to a memory in the CMM for example is needed to record the dimensions and characteristics of each specific end effector in a useable database. Thus, the system is limited in scope of application, and it is not a fully automatic recognition system or a readily, easily, or infinitely expandable system. It is also not dynamically configurable or configurable on the fly during measurement. For example, if a particular algorithm or particular data is used with the probe, since the Romer probe does not have a processor or a memory, the algorithms or data used with the probe could not be easily updated in the probe itself.